[tialaramex]

There is no "inevitable forgot to pay it off". Last century when I was old enough I got a credit card and the bank set it to automatically pay off every month. The bank says to itself, full balance of this account this month is say £462.83 and must be paid on or before the 7th of December, then it sets a transfer to occur from my checking account for the amount £462.83 on the 7th of December. No "forgetting" possible.

Indeed if say an IT problem occurs and they can't do that transfer under UK law they eat the fees incurred. "The customer must be made whole".

As to fees, the merchant doesn't have to accept cards, as we see with Amazon, if they don't like the fees. Why should ordinary consumers care? When we were part of the EU the cards couldn't charge excessive fees, now Brexit allowed them to unlock this potential source of profit.